Review of the New York Geological Reports. 61 
of Avicula, Cypricardia, Nucula, and other similar forms abound, 
with fewer of genera Orthis, Delthyris, &c. In the next divis- 
ion Delthyris, Strophomena, and Atrypa abound, to the almost 
entire exclusion of the forms before mentioned. In the same 
situations with these we find numerous species of corals: Cya- 
thophylli, Favosites, and other forms, are abundant; while frag- 
ments of crinoidal columns are every where scattered through 
the mass, or spread evenly over the surface, and form thin layers 
by themselves 
“The contrast in the prevailing fossils of this group with those 
of the last is as great as in the lithological products of the two 
formations. We sometimes indeed meet with a species that oc- 
urs in the limestone below, but except in a few instances these 
recognitions are rare. Some of the more abundant corals are 
identical, but the great number of new forms renders them of 
ess importance, and in all instances they are too few in number 
to produce any doubt or difficulty in identification of strata. 
“Shells both of the Brachiopoda and Dimyaria have comtaate 
increased, and in many single localities from twenty to fifty spe- 
cies may be obtained.” 
In Vanuxem’s district, where the lithological character of the 
Hamilton group is more arenaceous, the foll owing are the pre- 
vailing forms, as given by that author. 
Vanuxem’s Report. (36.) 
iat 1. Head of Dipleura DeKayi. 2. Orthonota undulata, 3. Delthyris mu- 
ies re bl hat the head of the Clinton and Niagara Trimerus, but 
beat according to Vanuxem, not only in the form of the snout, but also in the 
+ kay the eyes sae es ae full and ation ot in ond ape ura. Iti is @ Iso 
